Is it the fact he hasn’t turned in his research report?A. whetherB. thatC. whichD. why

问题补充：

Is it the fact he hasn’t turned in his research report?

A. whether

B. that

C. which

D. why

答案：

A. whether

(答案→)B. that

C. which

D. why

解析：本题考查同位语从句的引导词。结合句意“他还没有交调查报告是吗？”可知从句意义完整，引导词不做成分，所以选B。